The present disclosure relates to an operation device and a displacement adjustment method. More particularly, the present disclosure relates to an operation device and a displacement adjustment method that permits automatic displacement adjustment when a user uses a touch panel.
On an image forming apparatus, such as an electronic copier, that is furnished with multiple functions like an automatic document feed function, a facsimile exchange function, a scanner function, and a printer function, irrespective of which of those functions is being used, an operation panel keeps being operated. That is, the operation panel is used constantly.
Operation panels for incorporation in the operation section of image forming apparatuses, i.e., touch panels, are roughly classified into a capacitive type and a resistive-film type. In particular, the resistive-film type has long been in practical use, and has been used in numerous image forming apparatuses.
The resistive-film type has the following advantages among others: the hardware is inexpensive; it does not require a complicated algorithm to realize the function of a touch panel; it does not require high-performance ICs (integrated circuits) and components in the input interface and control circuitry; and the power consumption is small.
A touch panel of the resistive-film type is composed of a flexible film in the topmost layer disposed over a transparent substrate of glass or the like, and the reverse side of the film and the obverse side of the substrate are typically coated with a electrically conductive transparent film of ITO (indium tin oxide). Between the film and the substrate, “dots,” which are spacers of an electrically insulating material, are arrayed at predetermined intervals across the plane, so that a gap is left between the film an the substrate. When a user, with a finger or a stylus, presses the film from above the touch panel, at the point of the touch, the film makes contact with the electrically conductive transparent film on the inner side of the substrate, and this permits the pressed (touched) position to be identified.
On the disadvantageous side, a touch panel of the resistive-film type is liable to be influenced by EMI (electromagnetic interference) and humidity, and suffers from the analogue sensor output value varying with temperature and time. As a solution, conventionally, a change in the environment is coped with by performing calibration with no input so as to compensate for a displacement of the reference position (origin) with no input.
For example, a terminal device is known which includes a first input device for detecting a position or a specified quantity based on a user operation and a second input device for detecting presence of an object approaching the first input device. This terminal device is characterized by the provision of a controller which performs automatic calibration of the first input device, and which, when the second input device detects presence of an object approaching the first input device during the automatic calibration, stops the automatic calibration of the first input device. Thus, it is possible to prevent failure of automatic calibration due to the user making an operation during automatic calibration.
On the other hand, as a technology involving vibration applied to a touch panel, an input method is known which comprises a detection step of detecting approach or contact by a living body or an object within a predetermined detection range, a vibration step of causing vibration momentarily in response to detection of approach in the detection step, and an input step of performing a predetermined input process in response to detection of contact in a predetermined state in the detection step. Thus, immediately before a user touches the panel, he can see, by momentary vibration, that he can make an input by touching the position; the user can thus operate the touch panel reliably.